What is a UPF and why does it matter?

As UPF labels on clothes and swimsuits become more common, an increasing number of sun-lovers and outdoors people are left wondering: What is a UPF measure and how is it different from the SPF found on sunblock? Look no further to learn the ins and outs of UPF labeling. There’s nothing worse than assuming your clothes offer sun protection, only to find yourself burnt later. Actually, one thing is worse: having that happen to your child or a senior family member. 

UPF stands for Ultraviolet Protection Factor. It measures how much UVB and UVA radiation can hit your skin through the fabric. Together, these two are known as UV radiation. In number form, a UPF-30 fabric lets only 1/30th, or 3.33%, of the amount of sun through compared to what bare skin would experience.

Meanwhile, SPF (Sun Protection Factor), measures the amount of sun you receive when wearing sunscreen. The degree of sun filtering through sunscreen varies based on many factors: time spent in the sun, amount of sunscreen applied, time of day, the proximity to the equator, and even the ozone’s health in that area. That’s a lot of factors that vary with SPF! In the FDA’s official words:

"SPF is a measure of how much solar energy (UV radiation) is required to produce sunburn on protected skin (i.e., in the presence of sunscreen) relative to the amount of solar energy required to produce sunburn on unprotected skin."

SPF is best for comparing different sunscreens to one another. It’s not very informative for a person who’s rarely been exposed to bright sun or never worn sunscreen. It also doesn’t help a person heading on vacation in a new area know which to choose. Also, common sunscreen ingredients, like oxybenzone, have themselves been associated with problems that can cause cancer. Although some organic and less toxic sunscreens exist, a high-UPF garment, like 50+, is a safer (and easier) way to reduce sun exposure.

Although UPF and SPF are similar, UPF is more informative because it provides a number for the percentage of solar rays going through the fabric. Again, UPF also considers both UVA and UVB rays. When comparing garments, know that the Skin Cancer Foundation recommends at least a UPF of 30. Any fabric with a UPF letting in less than 2% of UV rays will say UPF 50+. That’s the highest UPF.

With UPF, the factors to consider are fewer than with SPF. Of course, the most important consideration is easy: how much skin will the clothes cover? Secondly, the opaqueness and thickness of the cloth are important. Ask yourself: How dense is the fabric? Denim, wool and many synthetic fibers trump those you can see through when held up to the light. Look for fabrics like unbleached cotton, shiny polyesters and tight silks. Some new, fancy fabrics are made to be nearly sunproof. These fabrics use chemical or dye technology to limit the amount of UV radiation that can shine through.

After considering the fabric itself, think about your future activities. If the fabric will stretch tight or get wet, be sure to purchase a garment with a higher UPF. However, most of the time, a garment with a UPF (especially one of 50+), still provides more consistent sun protection than what you’ll get in a bottle. Sunblock needs to be reapplied every few hours, and more often if it gets wet. However, wet polyester may protect better than dry polyester. Darker fabrics will also protect better than lighter ones. Of course, fabrics lose their protectiveness as they age, stretch out and lose color.

Those unfamiliar with UPF will be surprised to know washing your clothes can affect the UPF in positive ways. The protection factor can actually climb in some cases. If a fabric shrinks, it will have a higher UPF. That’s because the space between the fibers decreases. Also, some detergents with brighteners can raise the UPF, or at least maintain it. In general, fabrics that aren’t treated with a finish for a UPF don’t change much until they wear down. Those with protective finishes may fade over time. Often, the tag of a certain garment will state the number of washes it guarantees. 

After reading about the benefits of clothing labeled with a UPF, it’s important to protect everyone who needs it. UPF-labeled clothes are great for people who burn easily or have many freckles or moles. Children naturally have thinner, more sensitive skin. UPF clothing eliminates the constant application battle with sunblock. For kids, damage can compound over time. On that note, older adults also need extra sun protection too. Certain medications like complexion treatments, antibiotics, antihistamines, anti-inflammatories and others can make people prone to burning.

Most often, we focus on sun protection when going on beach or water vacations. However, if vacationing at high elevations, the air will be thinner and reflect off the snow. On any vacation, don’t forget to take into account how close you are to the equator. In some places, like Australia, the ozone is less protective as well. Finally, no guide to UPF would be complete without urging those with darker skin who are less sensitive to the sun to cover up. It’s harder to notice sun damage on darker skin until it’s too late.

Summary

1. What is a UPF and why does it matter?
2. How does UPF differ from SPF?
3. Who can benefit from wearing clothes with a UPF promise?
4. What do UPF ratings mean?

What is a UPF and why does it matter?

UPF is a measure of the percentage of UVA and UVB rays from the sun that can penetrate through a fabric to reach the skin. UPF is somewhat similar to SPF. However, it’s used to label clothing. The UPF of garments matters because of the increasing prevalence and incidence of skin cancer and skin problems. Also, common sunscreen ingredients, like oxybenzone, have themselves been associated with problems that can cause cancer. Although some organic and less toxic sunscreens exist, a high-UPF garment, like 50+, is a safer way to reduce sun exposure.

How does UPF differ from SPF?

UPF stands for Ultraviolet Protection Factor. It measures how much UVB and UVA radiation can hit your skin through the fabric. Together, these two are known as UV radiation. In number form, a UPF-30 fabric lets only 1/30th,  or 3.33%, of the amount of sun through compared to what bare skin absorbs.

Meanwhile, SPF, or Sun Protection Factor, measures the amount of sun you receive when wearing a particular sunscreen. There are many misconceptions about what the number of an SPF truly represents. According to the FDA, It’s a ratio of how much more solar energy is needed to produce a burn on protected skin versus unprotected skin. SPF is not a measure of how much longer (i.e. 30 times longer) it takes to get burnt while wearing that sunscreen. 

Who can benefit from wearing clothes with a UPF promise?

UPF clothing eliminates the constant application battle with sunblock. UPF-labeled clothes are great for people who burn easily. People with many freckles or moles also have increased risk for skin cancer. Children naturally have thinner, more sensitive skin. For kids, damage can compound over time. On that note, older adults also need extra sun protection too. People who work in the sun for hours at a time should consider UPF clothing as an alternative to sunscreen. It’s cheaper, easier, and doesn’t cause (cancerous) complications later. Certain medications like complexion treatments, antibiotics, antihistamines and anti-inflammatories, among others, can make people more prone to burning. Those going on vacations to other climates should consider buying clothing with a UPF. This is true for different latitudes, altitudes, water-side locales and places with ozone problems.

What do UPF ratings mean?

UPF (Ultraviolet Protection Factor) is a measure of the percentage of UV rays reaching the skin through that fabric. A UPF-30 fabric lets only 1/30th or 3.33%, of the amount of sun through compared to what bare skin absorbs. In short, it tells you how much of the sun’s potency is screened out by that fabric. A UPF of 50+ is considered excellent. The UPF rating system doesn’t go any higher than 50+.